JP2001099970A - Manufacturing method of fuel channel box, and fuel channel box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel channel box capable of executing oxide film forming treatment on the surface in a short time, and a fuel channel box. SOLUTION: After a zirconium base alloy plate material 10A is molded and welded to form a cylindrical shape, contact treatment with solution containing a metal alkoxide 10Z is given to a cylindrical fuel channel box 10D, to form a metal oxide film 16 on the surface, and the fuel channel box 10 is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a fuel channel box and a fuel channel box.
In particular, the present invention relates to a method of manufacturing a fuel channel box of a zirconium-based alloy member suitable for use in a boiling water reactor and a fuel channel box.

[0002]

2. Description of the Related Art As a material of a fuel channel box used for a fuel assembly of a boiling water reactor (BWR), sufficient mechanical strength at high temperature, small reaction with reactor cooling water, Due to conditions such as small thermal neutron absorption cross section, alloying elements Sn, Fe,
Zirconium-based alloys with a small amount of addition, such as Cr and Ni, are used. Each of the added alloy elements Sn, Fe, Cr,
Ni is mainly intended to improve corrosion resistance, hydrogen absorption resistance, workability, and mechanical properties. The chemical composition of the zirconium-based alloy is shown in Japanese Industrial Standard JIS H4751. At present, Zircaloy-4 and Zircaloy-2 among zirconium-based alloys are mainly used as fuel channel box materials.

[0003] During the transportation, transportation and assembly steps of the fuel channel box, if a flaw is formed on the surface of the fuel channel box, there is a concern that corrosion and hydrogen absorption may proceed from the flawed site. Therefore, conventionally, an oxide film is formed on the surface of the fuel channel box so as to eliminate the influence of scratches during transportation or the like. Here, as a conventional method for forming an oxide film, an autoclave treatment method in which the surface is oxidized in high-temperature steam is used.
It is covered with an approximately uniform thin oxide film of about m.

[0004]

However, the conventional autoclave treatment for forming an oxide film on the surface of the fuel channel box has a problem that the time required for the temperature increase, the oxidation treatment and the temperature decrease is long. That is, from room temperature to 400
It takes about 2-3 hours to raise the temperature to 400 ° C., and performs oxidation treatment at 400 ° C. for about 10 to 48 hours.
It took about 4 to 5 hours to lower the temperature from 00 ° C. to normal temperature.

An object of the present invention is to provide a method of manufacturing a fuel channel box and a fuel channel box which can perform an oxide film formation process on the surface in a short time.

[0006]

(1) In order to achieve the above object, the present invention relates to a fuel for forming a metal oxide film on a surface of a zirconium-based alloy sheet material by forming and welding the sheet into a cylindrical shape. In the method for manufacturing a channel box, the metal oxide film is formed by subjecting the cylindrical fuel channel box to a contact treatment with a metal alkoxide-containing solution. According to such a method, the time required for forming the metal oxide film can be reduced.

(2) In the above (1), preferably,
The main component of the metal element contained in the metal alkoxide-containing solution is zirconium.

(3) In the above (2), preferably,
Further, the metal element contained in the metal alkoxide-containing solution contains at least one of titanium, niobium, tin, iron and chromium. With this configuration, the corrosion resistance can be improved.

(4) In order to achieve the above-mentioned object, the present invention provides a method for forming and welding a zirconium-based alloy sheet material into a cylindrical shape and then applying a metal oxide coating film on the surface thereof by a contact treatment with a metal alkoxide-containing solution. It is to be formed. With this configuration, the time required for forming the metal oxide film can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a fuel channel box according to an embodiment of the present invention will be described below with reference to FIGS. First, referring to FIGS. 1 and 2,
The manufacturing process of the fuel channel box according to the present embodiment will be described. FIG. 1 is a process diagram showing a manufacturing process of the fuel channel box according to the present embodiment, and FIG.
It is an external appearance perspective view of the component in each manufacturing process of the fuel channel box by this embodiment.

In step P10 of FIG. 1, a zirconium-based alloy material plate (zircaloy plate material) 1 shown in FIG.
OA is produced. The zircaloy plate material 10A is a zirconium-based alloy, for example, a slag is formed by hot forging an ingot of zircaloy-4 or zircaloy-2,
The slag is produced by solutionizing the slag and repeating heat treatment and rolling. Next, in a process P20 in FIG. 1, a plate material such as a surface and a plate thickness of the material plate is inspected.

Next, in step P30 of FIG. 1, the zirconium-based alloy plate material 10A is formed into a U-shape as shown in FIG. Next, in step P40 of FIG. 1, the two U-shaped forming plates 10B formed in step P30 are butted and automatically welded to form a rectangular tube as shown in FIG. The beat portion is flattened to form a rectangular cylindrical channel box 10C.

Next, in step P50 of FIG. 1, an inspection of the welded portion is performed. That is, a non-destructive inspection is performed on the rectangular tube-shaped channel box 10C formed in the process P40 by an ultrasonic flaw detection method or the like to check whether the welding is properly performed. Next, in step P60 of FIG. 1, stress relief annealing is performed. That is, a process for maintaining a predetermined dimensional accuracy is performed while performing a heat treatment for removing a residual stress in a welded portion or a formed bent portion. The heat treatment includes α + β quenching or β quenching.

Next, in step P70 of FIG.
(D) As shown in FIG.
The clip 12 is welded to the open end of C, and the channel spacer 14 is welded to the side surface. Next, step P80 in FIG.
In the above, the surface of the rectangular cylindrical channel box 10C is polished to remove the oxide film formed by the heat treatment.
Next, in step P90 of FIG. 1, fine scratches and dirt on the surface are removed by pickling and washing.

Next, in step P100 of FIG. 1, a metal oxide film (coding film) containing zirconium as a main component is formed on the surface of the fuel channel box 10D. The metal oxide film is, as shown in FIG.
It is formed by subjecting the surface of the fuel channel box 10E to a contact treatment with a solution 10Z containing a metal alkoxide. By bringing the fuel channel box made of glucaroy material into contact with the metal alkoxide solution,
By the hydrolysis, the zircaloy becomes zircaloy oxide to form a film. As a specific method of the contact treatment with the metal alkoxide solution, for example, 1) a method in which the fuel channel box is immersed in a solution containing a metal alkoxide containing zirconium as a main component and then pulled up (dip coating), 2 There is a method of spraying, spraying, spraying, and applying a solution containing a metal alkoxide to a fuel channel box. The metal oxide film has strong adhesion even at room temperature, and is in an amorphous state. By contact treatment (immersion, spraying, application) of metal alkoxide solution and fuel channel box,
A metal oxide film can be formed on 50% or more of the surface.

As the metal alkoxide, for example, a zirconium (Zr) alkoxide is used. Zirconium (Zr) alkoxides include Zr ethoxide, Zr
Propoxide, Zr butoxide, or the like can be used. In the metal alkoxide solution 10Z, titanium (Ti), niobium (Nb), tin (Sn) having a catalytic action,
One or more of iron (Fe) and chromium (Cr) may be mixed. By mixing these metals, corrosion resistance is improved and hydrogen absorption can be suppressed. The thickness of the metal oxide coating can be adjusted by adjusting the component concentration and viscosity of the solution 10Z containing the metal alkoxide, the speed of immersion and pulling up in the solution 10Z containing the metal alkoxide, and the number of repetitions.

The thickness of the metal oxide film formed on the surface of the fuel channel box is 0.01 to 1 μm.
The metal oxide film is mainly composed of zirconium metal,
That is, the zirconium metal is 50 wt% or more. In addition, 0.1% by weight based on zirconium
One or more of the above titanium, niobium, iron and chromium may be contained. For example, the metal oxide coating comprises 97.5 wt% zirconium metal and 2.5 wt%
% Titanium.

The formation of the metal oxide film should be at least 50% or more of the surface of the fuel channel box in order to prevent the formation of scratches on the surface of the fuel channel box during the transportation, transportation and assembly steps. Is preferred.

After the metal oxide film is formed, heat treatment may be performed. The heating temperature and time at this time are lower than the temperature at which zirconium is partially recrystallized, and the heat treatment time is about 2 to 10 minutes. Since the temperature at which the partial recrystallization of zirconium starts is about 500 ° C., the heat treatment temperature is, for example, 80 ° C.
To 100 ° C. Furthermore, since the metal oxide film formed on the surface of the fuel channel box by the contact treatment with the metal alkoxide solution is in an amorphous state,
By performing heat treatment at a temperature equal to or higher than the partial recrystallization temperature of zirconium, a crystalline metal oxide film may be formed.

Next, in step P110 in FIG. 1, the spacer and the rivet are welded to the fuel channel box. This step P110 is performed before the step P100 (step P9).
0 after the pickling step). Next, in a step P120 in FIG. 1, a final inspection of the product is performed. In the appearance inspection, the surface is inspected for the presence or absence of surface flaws and dirt. In the dimensional inspection, the plate thickness, squareness, internal dimensions, swelling, straightness and parallelism to the reference plane are inspected.

Based on the above steps, step P13 in FIG.
At 0, as shown in FIG. 2 (F), a fuel channel box 10 as a final product is manufactured.

Next, the configuration of the metal oxide film forming apparatus in the method of manufacturing the fuel channel box according to the present embodiment will be explained with reference to FIG. After the processing up to the step P90 shown in FIG. 1 is completed, the fuel channel box 10D that has been polished, pickled, and cleaned is transported by the transport device 110 to the injection devices 120A, 120B, 120C, and 120.
It is moved to the position of D, 120E. Therefore, the fuel channel having a metal oxide film formed on the surface by spraying, spraying or spraying the metal alkoxide-containing solution 10Z on the surface of the fuel channel box 10D by the injectors 120A, 120B, 120C, 120D, 120E. A box 10E is formed. The injection device 120A is
The metal alkoxide-containing solution 10Z is sprayed or the like inside the fuel channel box 10D,
B, 120C, 120D, and 120E spray the metal alkoxide-containing solution 10Z on the outer peripheral side of the fuel channel box 10D. Metal alkoxide containing solution 1
The time required for forming the metal oxide film by spraying 0Z or the like is about 30 minutes.

The sprayed or sprayed or sprayed liquid is collected by a collecting tank 130, and after adjusting the component concentration to a predetermined concentration, the liquid is passed through the injection line 150 by the circulation device 140 and reused in the injection device 120 again.

The measuring device 160 measures the component concentration of the metal alkoxide-containing solution 10Z. Then, using the injection system 170, the metal alkoxide solution or solvent can be added continuously or intermittently, and the concentration of the metal alkoxide-containing solution 10Z is adjusted to a predetermined concentration.

Next, with reference to FIG. 4, the results of a corrosion test of a metal oxide film formed by the method for manufacturing a fuel channel box according to the present embodiment will be described. FIG.
4 is a graph showing a result of a corrosion test of a metal oxide film formed by a method of manufacturing a fuel channel box according to an embodiment of the present invention.

The vertical axis of FIG. 4 indicates the amount of corrosion. FIG.
Assuming that the corrosion amount in the test piece shown in (a) is 1, the relative value of the corrosion amount in the other test pieces is shown. When the amount of corrosion is smaller than 1, it indicates that the amount of corrosion is smaller than the amount of corrosion in the test piece shown in FIG.

As a test piece, a Zircaloy-2 alloy is used. FIG. 4A shows an untreated material without a metal oxide film. 4 (b), (c),
(D) shows a metal oxide film having a thickness of about 0.12 μm formed by dipping in a Zr alkoxide solution and pulling up. 4 (b), (c), and (d), the metal components of (b) are only Zr, and (c) are about 2.5 wt% of Zr. Niobium is contained, and (d) is titanium-containing about 2.5 wt% with respect to Zr.

These test pieces were simultaneously subjected to a corrosion test for 120 hours in steam at 450 ° C., and after the test, the weight increase was measured. As a result, when the metal oxide film of about 0.12 μm was formed with the Zr alkoxide solutions of (b), (c) and (d), the amount of corrosion was smaller than that of the untreated (a). There is a suppression effect. In addition, the corrosion inhibition effect was equivalent to that of the conventional autocrepe treatment.

Next, the structure of the fuel channel box formed by the method of manufacturing the fuel channel box according to the present embodiment will be described with reference to FIGS. FIG. 5 is a perspective view of a fuel channel box formed by the method of manufacturing a fuel channel box according to the present embodiment, and FIG. 6 is a cross-sectional view taken along line AA of FIG.

On the surface of the fuel channel box 10,
A zirconium-based metal oxide film 16 formed of a solution containing a metal alkoxide has a thickness of 0.01.
１1 μm.

Next, the configuration of a BWR fuel assembly to which the fuel channel box according to the present embodiment is applied will be described with reference to FIG. FIG. 7 is a side sectional view showing a configuration of a fuel assembly of a BWR to which a fuel channel box according to an embodiment of the present invention is applied.

The fuel assembly is composed of a plurality of fuel rods 50 loaded with nuclear fuel pellets in a fuel cladding tube and welded at both ends, a water rod 60 disposed between the fuel rods 50, a fuel rod 50 and a water rod 60. A plurality of fuel spacers 70 for appropriately maintaining the intervals, an upper tie plate 80 and a lower tie plate 90 for supporting the upper and lower ends of the fuel rods 50, and zirconium as the main component on the surface of the rectangular tube for accommodating them. And a fuel channel box 10 on which a metal oxide film 16 is formed.

The outline of the process of assembling the fuel assembly is as follows. After the water rod 60 with the fuel spacer 70 attached is inserted into the lower tie plate 90 and fixed with a jig, a number of fuel rods 50 and tie rods are passed through the fuel spacer 70 and attached to the lower tie plate 90. The tie rod is screwed into the lower tie plate 90 and fixed while the fuel rod 50 is still inserted in the lower tie plate 90. Then, after attaching a spring to the upper part of the fuel rod 50, the upper tie plate 80 is fitted and screwed to the tie rod to form a fuel bundle. Then, before loading the reactor, the fuel bundle, the manufactured fuel channel box 10 and the channel fastener are attached to form a fuel assembly.

The fuel rod 50 and the water rod 60 are
8 × 8 or 9 × in the fuel channel box 10
It is assembled squarely in a suitable arrangement with 9 or 10 × 10 fuel spacers 70.

According to the present embodiment, the metal oxide film is formed on the surface of the fuel channel box, so that the surface of the fuel channel box 10 is flawed during the transportation, transportation and assembly process of the fuel channel box 10. Therefore, it is possible to obtain a fuel channel box capable of suppressing corrosion from scratches. Since the formation of the metal oxide film is performed by a contact treatment with a metal alkoxide solution, the metal oxide film formation treatment can be performed in a short time.

In recent years, BWRs have been working to increase the burnup of fuel in order to improve the economy, but it is also possible to cope with the increase in burnup by forming a metal oxide film. . Further, along with this, extension of the service life of the fuel channel box of the fuel assembly member has been studied similarly to the fuel, but it is possible to cope with such a long-term cycle operation.

[0037]

According to the present invention, the process of forming an oxide film on the surface of the fuel channel box can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a process diagram illustrating a manufacturing process of a fuel channel box according to an embodiment of the present invention.

FIG. 2 is an external perspective view of components in each manufacturing process of the fuel channel box according to one embodiment of the present invention.

FIG. 3 is a configuration diagram of an apparatus for forming a metal oxide film in a method of manufacturing a fuel channel box according to an embodiment of the present invention.

FIG. 4 is a graph showing a result of a corrosion test of a metal oxide film formed by a method of manufacturing a fuel channel box according to an embodiment of the present invention.

FIG. 5 is a perspective view of a fuel channel box formed by a method of manufacturing a fuel channel box according to an embodiment of the present invention.

6 is a sectional view taken along line AA of FIG.

FIG. 7 is a side sectional view showing a configuration of a fuel assembly of a BWR to which a fuel channel box according to an embodiment of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Fuel channel box 10Z ... Metal alkoxide solution 12 ... Clip 14 ... Channel spacer 16 ... Metal oxide film 50 ... Fuel rod 60 ... Water rod 70 ... Fuel spacer 80 ... Upper tie plate 90 ... Lower tie plate 110 ... Conveying device 120 ... Injection device 130 ... Recovery tank 140 ... Circulation device 150 ... Injection line 160 ... Measuring device 170 ... Injection system

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshitaka Nishino 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Power and Electricity Research Laboratory, Hitachi, Ltd. (72) Inventor Takehiro Seto, Sachiyuki Hitachi, Ibaraki Prefecture 3-1-1, Machi-cho, Hitachi, Ltd. Atomic Energy Division, Hitachi, Ltd. (72) Inventor Takayoshi Yasuda 3-2-1, Sachimachi, Hitachi-shi, Ibaraki Prefecture, Hitachi Engineering Co., Ltd.

Claims (4)

[Claims] 1. A method for manufacturing a fuel channel box, comprising forming a metal oxide film on a surface of a zirconium-based alloy plate by forming and welding a zirconium-based alloy plate material. A method for producing a fuel channel box, wherein the metal oxide film is formed by performing a contact treatment with an alkoxide-containing solution. 2. The method for manufacturing a fuel channel box according to claim 1, wherein the main component of the metal element contained in the metal alkoxide-containing solution is zirconium. 3. The method for producing a fuel channel box according to claim 2, wherein the metal element contained in the metal alkoxide-containing solution further comprises:
At least one of titanium, niobium, tin, iron and chromium
A method for manufacturing a fuel channel box, comprising a type. 4. A fuel channel box wherein a zirconium-based alloy sheet is formed and welded into a cylindrical shape, and then a metal oxide film is formed on the surface thereof by a contact treatment with a solution containing a metal alkoxide.